Spintronics relates to use of spin of electrons in various types of devices, such as oscillators and random access memory (RAM). Several such prior art devices use an electrically resistive layer between two layers of metallic magnets, to form a magnetic tunnel junction (MTJ). One of the just-described two metallic magnets has its magnetization fixable into one of two directions in a plane of the layer of the magnet, depending on a direction of electric current. The magnetization of the other of the two metallic magnets can rotate in the plane of the layer. Passage of an electric current through the fixable-magnetization layer generates a spin current, whose absorption in the rotatable-magnetization layer gives rise to a spin transfer torque that changes the direction of magnetization of the rotatable-magnetization layer.
For additional details on such a three layered structure, see an article entitled “Magnetic-field Tunnel-sensor” by J. C. Slonczewski published in the IBM Technical Disclosure Bulletin. vol. 19. No. 6. Nov. 1976. pp. 2331-2332, which is incorporated by reference herein in its entirety as background.
In several devices of the prior art, electric current flows through an electrically conducting polarizing magnet, to generate a spin current whose absorption gives rise to a torque in a free magnet. As additional background, the following patents are incorporated by reference herein in their entirety:
(a) U.S. Pat. No. 5,695,864 granted to Slonczewski on Dec. 9, 1997, and entitled “Electronic device using magnetic components”;
(b) U.S. Pat. No. 7,149,106 granted to Mancoff, et al. on Dec. 12, 2006, and entitled “Spin-transfer based MRAM using angular-dependent selectivity”;
(c) U.S. Pat. No. 7,808,330 granted to Fukuzawa, et al. on Oct. 5, 2010 and entitled “High-frequency oscillator”;
(d) U.S. Pat. No. 6,771,534 granted to Stipe on Aug. 3, 2004, and entitled “Thermally-assisted magnetic writing using an oxide layer and current-induced heating.”
As further background, the following articles are also incorporated by reference herein in their entirety:
(f) Hatami et al, Phys. Rev. Lett. 99, 066603 (2007) “Thermal Spin-Transfer Torque in Magnetoelectronic Devices”; and
(g) Yu et al, Phys. Rev. Lett. 104, 146601 (2010) “Evidence of thermal spin-transfer torque.”